Full-On 2 Storey Extension

[stef99]

Hi, Everyone, I've started building my 2 storey extension recently.
I will be doing some of the work myself, but most of it will be done by a brick layer.

So far I have dug out my foundations and will be contacting Building control before I begin to pour my concrete.

I have dug down to the clay, and to a depth of 1.2m

I have been told by my brick layer that foundations should be in multiples of 75mm (the height of the bricks.

So... for setting my levels I assume that I go down from my floor levels approximately 900mm and fill the rest with my footings.

this would make my foundations about 400mm thick which is over the required 300mm

does this correct?

 

[noseall]

You should work out your finished foundation concrete height relative to the house DPC and not necessarily the house floor level although this is usually the case.

Yes, work in 75mm increments down from DPC.

Take into account some DPC's are ultra thick (like slate bed) so adjust your finished DPC masonry height accordingly.

Take into consideration also that the house may not be level so peg down from the lowest point of the house or halve the deficit.

Ideal distance down from DPC is 525mm if external ground levels permit.

Mass filling is ideal so a thicker than stipulated concrete footing is typical and not at all unusual.